Kinetics of ferrocyanide reduction of quinones

We describe here the kinetics of ferrocyanide reduction of 2,5-dichloro-, benzo-, and 2,5-dimethylquinones (denoted below by I, II, III) in 1 M KCl. Reagent materials were used where available and the hydroquinones of I and III were synthesized by SnCl_2 reduction and recrystallization. Slightly alcoholic solutions of quinone in 1 M KCl were deoxygenated, placed in blackened vessels at 27°, and then in a 10-cm path Beckman cell. Buffered 1 M KCl ferrocyanide at 27° was added and the rate was measured from ferrocyanide disappearance at 420 mµ or disappearance of I at 275 mµ, using a Beckman.